A High-Definition Multimedia Interface (HDMI) connection provides for uncompressed delivery of digital video content between a source device and a display device that conform to published specifications and standards. The existing standards (CEA-861E) and specifications (HDMI v1.3), however, provide for a wide range of video formats, e.g., standard definition (SD) and high definition (HD) at various picture sizes and frame rates. Because there are plethora of video transmission options that operate within the boundaries of the existing standards and specifications, the display devices are not necessarily restricted or otherwise configured to operate with a specific one of the options—there is no specific requirement for the carriage of video content between the source device and the display device. The video formatting requirements of the output devices, therefore, are decided by the manufacturers and tend to vary from one manufacturer to another.
For example, one manufacturer may use an over/under coding for 3D video where the separate left and right video images are packed into a single video frame with the left frame over the right frame, but squeezed into a single video frame. The video signals on the interface are fully compliant in every way with the existing standard except the source and display devices must some how understand that for 3D content the first (upper) half of the video frame will be used for the “left-eye” image while the second (lower) half of the video frame will be used for the “right eye” image. As long as the exchange is understood and used in the same way by both of the source and display devices, compatibility is provided. Other manufacturers may use a similar scheme, but choose to place the left and right images side-by-side within a single frame. Still others alternate lines, pixels or frames between left and right source images. In addition to the spatial division and placement of the separate left and right signals, other techniques can be used, including inversion or mirroring of one signal versus the other.
Manufacturers deploying display devices are taking advantage of existing video formatting modes of the HDMI connection but with a private or a priori knowledge of the formatting requirements of the display device. In other words, the manufacturers are relying on the source device to have prior knowledge of the formatting requirements of the display device such that the source device can be deployed with the same design principles as the display device. As a result, even though a multitude of different and incompatible choices are possible, interoperability between the source device and display device is only possible between products designed according to the same formatting principals.
In environments where source devices are commonly deployed to subscribers or other locations where the formatting requirements of the display devices is unknown or not necessarily the same for each display device, there is a possibility of format incompatibility between the source device and the display device.